This invention relates to copy sheet transport systems, and more particularly, to an improved prefuser vacuum transport for copy sheets transported in a copier/printer.
In copier/printer machines, it is common to transport sheets from the photoreceptor to the fuser by means of a multi-belt vacuum transport. Substantial vacuum pressure is usually desirable to provide adequate control over each sheet. This is especially true in machines where the unfused toner image is on the underside of the sheet and the sheet must be suspended from the underside of the vacuum transport. Other factors such as paper curl, cockle and high stiffness also increase pressure requirements.
When a sheet is exiting a photoreceptor horizontally the lead edge portion of the sheet is cantilevered until it is acquired by the vacuum transport. In applications where the vacuum transport is above the sheet, the effects of gravity add to the problem of acquisition due to sheet droop. This droop, in addition to sheet curl and sheet bending stiffness result in sensitive positioning of the vacuum transport with respect to the photoreceptor, especially when the copier/printer is to handle 110 pound index paper. Thus, it would be an advantage to solve the problem of getting the vacuum source closer to the sheet in order to effectively transport heavy weights of paper.